kernel: remove unused kernel_compat

Co-authored-by: weishu <twsxtd@gmail.com>

kernel/seccomp_cache.c

@@ -0,0 +1,192 @@
+#include <linux/version.h>
+#include <linux/fs.h>
+#include <linux/nsproxy.h>
+#include <linux/filter.h>
+#include <linux/seccomp.h>
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 10, 0)
+#include <linux/sched/task.h>
+#else
+#include <linux/sched.h>
+#endif
+#include <linux/uaccess.h>
+#include "klog.h" // IWYU pragma: keep
+#include "seccomp_cache.h"
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(4, 10, 0) ||    \
+    defined(CONFIG_IS_HW_HISI) ||    \
+    defined(CONFIG_KSU_ALLOWLIST_WORKAROUND)
+#include <linux/key.h>
+#include <linux/errno.h>
+#include <linux/cred.h>
+struct key *init_session_keyring = NULL;
+
+static inline int install_session_keyring(struct key *keyring)
+{
+    struct cred *new;
+    int ret;
+
+    new = prepare_creds();
+    if (!new)
+        return -ENOMEM;
+
+    ret = install_session_keyring_to_cred(new, keyring);
+    if (ret < 0) {
+        abort_creds(new);
+        return ret;
+    }
+
+    return commit_creds(new);
+}
+#endif
+
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 8, 0) || defined(KSU_OPTIONAL_STRNCPY)
+long ksu_strncpy_from_user_nofault(char *dst, const void __user *unsafe_addr,
+                   long count)
+{
+    return strncpy_from_user_nofault(dst, unsafe_addr, count);
+}
+#elif LINUX_VERSION_CODE >= KERNEL_VERSION(5, 3, 0)
+long ksu_strncpy_from_user_nofault(char *dst, const void __user *unsafe_addr,
+                   long count)
+{
+    return strncpy_from_unsafe_user(dst, unsafe_addr, count);
+}
+#else
+// Copied from: https://elixir.bootlin.com/linux/v4.9.337/source/mm/maccess.c#L201
+long ksu_strncpy_from_user_nofault(char *dst, const void __user *unsafe_addr,
+                   long count)
+{
+    mm_segment_t old_fs = get_fs();
+    long ret;
+
+    if (unlikely(count <= 0))
+        return 0;
+
+    set_fs(USER_DS);
+    pagefault_disable();
+    ret = strncpy_from_user(dst, unsafe_addr, count);
+    pagefault_enable();
+    set_fs(old_fs);
+
+    if (ret >= count) {
+        ret = count;
+        dst[ret - 1] = '\0';
+    } else if (ret > 0) {
+        ret++;
+    }
+
+    return ret;
+}
+#endif
+
+long ksu_strncpy_from_user_retry(char *dst, const void __user *unsafe_addr,
+                   long count)
+{
+    long ret;
+
+    ret = ksu_strncpy_from_user_nofault(dst, unsafe_addr, count);
+    if (likely(ret >= 0))
+        return ret;
+
+    // we faulted! fallback to slow path
+    if (unlikely(!ksu_access_ok(unsafe_addr, count))) {
+#ifdef CONFIG_KSU_DEBUG
+        pr_err("%s: faulted!\n", __func__);
+#endif
+        return -EFAULT;
+    }
+
+    // why we don't do like how strncpy_from_user_nofault?
+    ret = strncpy_from_user(dst, unsafe_addr, count);
+
+    if (ret >= count) {
+        ret = count;
+        dst[ret - 1] = '\0';
+    } else if (likely(ret >= 0)) {
+        ret++;
+    }
+
+    return ret;
+}
+
+long ksu_copy_from_user_nofault(void *dst, const void __user *src, size_t size)
+{
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 8, 0)
+    return copy_from_user_nofault(dst, src, size);
+#else
+    // https://elixir.bootlin.com/linux/v5.8/source/mm/maccess.c#L205
+    long ret = -EFAULT;
+    mm_segment_t old_fs = get_fs();
+
+    set_fs(USER_DS);
+    // tweaked to use ksu_access_ok
+    if (ksu_access_ok(src, size)) {
+        pagefault_disable();
+        ret = __copy_from_user_inatomic(dst, src, size);
+        pagefault_enable();
+    }
+    set_fs(old_fs);
+
+    if (ret)
+        return -EFAULT;
+    return 0;
+#endif
+}
+
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 10, 2) // Android backport this feature in 5.10.2
+struct action_cache {
+    DECLARE_BITMAP(allow_native, NR_syscalls);
+#ifdef SECCOMP_ARCH_COMPAT
+    DECLARE_BITMAP(allow_compat, SECCOMP_ARCH_COMPAT_NR);
+#endif
+};
+
+struct seccomp_filter {
+    refcount_t refs;
+    refcount_t users;
+    bool log;
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(6, 1, 0)
+    bool wait_killable_recv;
+#endif
+    struct action_cache cache;
+    struct seccomp_filter *prev;
+    struct bpf_prog *prog;
+    struct notification *notif;
+    struct mutex notify_lock;
+    wait_queue_head_t wqh;
+};
+
+void ksu_seccomp_clear_cache(struct seccomp_filter *filter, int nr)
+{
+    if (!filter) {
+        return;
+    }
+
+    if (nr >= 0 && nr < NR_syscalls) {
+        clear_bit(nr, filter->cache.allow_native);
+    }
+
+#ifdef SECCOMP_ARCH_COMPAT
+    if (nr >= 0 && nr < SECCOMP_ARCH_COMPAT_NR) {
+        clear_bit(nr, filter->cache.allow_compat);
+    }
+#endif
+}
+
+void ksu_seccomp_allow_cache(struct seccomp_filter *filter, int nr)
+{
+    if (!filter) {
+        return;
+    }
+
+    if (nr >= 0 && nr < NR_syscalls) {
+        set_bit(nr, filter->cache.allow_native);
+    }
+
+#ifdef SECCOMP_ARCH_COMPAT
+    if (nr >= 0 && nr < SECCOMP_ARCH_COMPAT_NR) {
+        set_bit(nr, filter->cache.allow_compat);
+    }
+#endif
+}
+#endif